Using transesophageal echocardiography during open heart operations, we found another form of retained intracardiac air, "pooled air," in addition to the form of "bubbles" that had been reported by other authors. The pooled air was detected in all of 13 patients (100%); it was located at the right upper pulmonary vein in 13 (100%), left ventricular apex in 9 (69.2%), left atrium in 8 (61.5%), right coronary sinus of Valsalva in 8 (61.5%), left atrial appendage in 4 (30.8%), and left upper pulmonary vein in 3 (23.1%). The pooled air was found also in the pulmonary artery in 6 of 8 patients (75.0%) in whom the pulmonary artery was clearly visualized. In 1 patient, 5 mL of air was aspirated from the left ventricular apex, followed by a reduced size of the air on the transesophageal echocardiographic image. Because intracardiac air rapidly changes its locations and appearances, continuous monitoring is important, especially at weaning from bypass. The long-axis view of the heart is useful not only for detecting and locating the air, but also for guiding and evaluating the procedures to remove air.